The present invention relates to collapsible container such as a collapsible pallet container for transport and storage.
Collapsible containers of the foldable pallet container type, are rather popular since they will make a radical saving of the empty return transport volume possible. Foldable pallet containers are advantageously made of thermoplastic materials which will give light and still sturdy containers which are easy to keep clean. Another advantage is that the tare-weight of such containers is very stable which is not the case with, for example, wood containers where the tare-weight can double when the wood becomes wet. Yet another advantage is that thermoplastic materials do not corrode, which is the case with containers made from metal such as steel and aluminium. Most thermoplastic materials furthermore have a good resistance to chemical substances such as acids and bases, which is not the case with most metals.
Most collapsible containers available suffer from the disadvantage that the usable internal height is limited by the width of the container since the foldable part of the side walls, of practical reasons, needs to be kept within the base dimensions when folded. It is therefore necessary to design containers with large base dimensions when larger heights are required. It is sometimes desirable to have containers with smaller base dimensions and larger height due to handling in small spaces.
It has, through the present invention, been made possible to solve the above mentioned problem, wherein a collapsible container with a new height to width ratio has been achieved. The invention relates to a collapsible container, preferably a collapsible pallet container for transport and storage, which collapsible container includes a carrying base part with a width W and a length L. It further includes collapsible side walls, which are constituted by short side walls and long side walls. The side walls are moveably attached to the base part. Adjacent side walls are inter-connectable. The invention is characterised in that, at least the two long side walls each are provided with a first and a second horizontal folding line by being provided with hinges. The first horizontal folding line constitutes a lower end of the side wall at which the side wall connects with the base part. The second horizontal folding line, which divides the side wall into an upper side wall part and a lower side wall part, is placed at a distance from the first horizontal folding line, between the lower end and an upper rim of the side walls. The two horizontal folding lines are mainly parallel. The long side walls extends to a height H above a load surface of the base part when erected. The height H is preferably larger than the width W. The lower side wall part is preferably larger than, or mainly as large as, the upper side wall part.
According to one embodiment of the invention the two short side walls are provided with uninterrupted rigid sections extending from the lower end to the upper rim, reaching the height H above the load surface when erected. The rigid sections are possibly provided with a flange intended to guide and join with the vertical edge of the adjacent side wall when erected.
The first horizontal folding lines of the long side walls are preferably arranged on a height h1 and h2 respectively, above the load surface while the first and only horizontal folding lines of the short side walls are arranged on a height h3 and h4 respectively, above the load surface, whereby h1 less than h2 and h2 less than h3 and h3 less than h4 so that the short side walls are folded over the long side walls. The first and/or the second horizontal folding lines are possibly constituted by so called live hinges. According to a preferred alternative the first and/or the second horizontal folding lines are constituted by hinges made of at least two parts which two parts each possibly constitutes an integrated part of the base part, a short side wall, an upper side wall part or a lower side wall part while possible additional parts constitutes intermediate parts arranged between the two parts. It is of course possible that the first or the second horizontal folding lines are constituted by a so called live hinge.
It is, according to one embodiment of the invention, advantageous to arrange the first horizontal folding lines of the long side walls so that they can be displaced vertically between a height h1xe2x80x2 and h1xe2x80x3, and a height h2xe2x80x2 and h2xe2x80x3 respectively, above the load surface. The first and only horizontal folding lines of the short side walls are arranged on a height h3 and h4 respectively, above the load surface. As in the embodiment above, h1xe2x80x2 less than h2 and h2xe2x80x2 less than h3 and h3 less than h4, wherein the short side walls are folded over the long side walls.
The vertical edges of the long side walls are preferably provided with gripping means intended to engage corresponding means, placed on the flanges of the short side walls. The gripping means engages the corresponding means by a vertical movement downwards so that the long side walls becomes mechanically locked to the short side walls, preventing the long side walls from folding inwards, unless lifted upwards.
The base part preferably has the basic shape of a pallet provided with feet and skids making it possible to handle the container with mechanical means such as a fork lift.
The collapsible container is preferably manufactured through injection moulding, vacuum moulding, blow moulding or press moulding of one or more polymeric materials such as polyethylene, polypropylene, polybutene, polyvinylchloride, polyalkylene-therephtalate, acrylonitrile-butadiene-styrene copolymer, polyamide, polycarbonate or the like. Since the desired material characteristics of the different parts that the container is made up of can vary from part to part it is possible to add different additives to the thermoplastic material that will make this possible. As examples of such known additives can be mentioned ethylene-vinyl-acetate and rubber beads which will make the material more ductile and more impact resistant, but on the other hand more disposed to thermal creepage, or glass fibre, carbon fibre, steel fibre or aramide fibre which will make the material more rigid, less disposed to thermal creepage but on the other hand more brittle.